1. Field of the Invention
The invention relates to a magnetic resonance imaging device, comprising a magnet system for generating a steady, uniform magnetic field and for generating magnetic gradient fields, an r.f. transmitter and receiver for generating and detecting magnetic resonance signals, and a processing and control unit for processing the detected resonance signals and for controlling the r.f. transmitter and receiver and the magnet system, the transmitter generating a transmission signal whose frequency deviates from the frequency of a reference signal to be applied to the receiver for demodulating a resonance signal generated by means of the transmission signal, there also being provided a sampling circuit for sampling the demodulated resonance signal.
2. Description of the Prior Art
A device of this kind is known from European patent application No. 0,165,057 corresponding to U.S. Pat. No. 4,654,597 to Hino. This European patent application describes the importance of a reliable and accurately operating r.f. transmitter and receiver. It also describes how the accuracy of a r.f. transmitter can be improved by using digital switching techniques for generating the modulation signal whereby the carrier is modulated. However, the r.f. receiver is still subject to drift and offset problems, because it may be assumed that it comprises the quadrature detection device customarily used for MRI applications. Drift and offset problems produce undesirable effects, for example stroke patterns, grey level shift etc., in the image to be ultimately reconstructed.